In recent years, a market has developed for sleeving which is used for sound absorption, particularly in sound proofing vehicles. Sleeving is provided over linkages, wires, tubes and similar movable parts, particularly where those parts are located behind panels of the vehicle, to muffle the sound made by such parts should they move in operation or be shaken while the vehicle moves. Textile fabric sleeves employing long lasting, textured, polymer plastic filament yarns are particularly desirable for use in premium automobiles, which provide one of the major markets for these products, because of their softness and bulkiness for sound reduction and their durability for long life.
Original sleeves were made from only interthreaded multifilament textured yarns. These sleeves were difficult to install. If knitted, they could be stretched to assist in installation but would not regain their original diameters and so could sag and/or move about. Braided sleeves can be somewhat contracted in diameter by stretching. However, unless tension can be maintained, they would expand in size and also sag and/or move about.
At least one known type of sound absorbent fabric sleeve is formed from textured, plastic multifilament bulky yarns and separate plastic monofilaments braided together. These sleeves are improvements over earlier sleeves formed of only the bulky, textured yarns. The bulky yarn/monofilament sleeves can be expanded to twice their nominal diameters or more by compressing the sleeves in their length directions to facilitate their installation and to permit their use on elements larger in size than the nominal diameters of such sleeves. Such sleeves are also capable of resiliently returning towards their nominal diameters in order to compress around the objects on which they are mounted so as to remain in their mounted positions.
While the bulky yarn/monofilament sleeves have distinct advantages over the earlier, all bulky yarn sleeves, they have at least one disadvantage. A hard spot is created where each monofilament crosses another monofilament in the braid. Each crossover creates a potential sound generating or at least non-absorbing spot along the sleeve. It would be desirable to provide a sound absorbent sleeve having the resilience of the above monofilament/multifilament sleeve but without the potential sound generating hard spots.